The Bureau of Land Management (BLM) released a revised biological assessment for BrightSource Energy's Ivanpah Solar Energy Generating System, indicating the likely presence of a high density of endangered desert tortoises on the 5.6 square mile swath of public land. The revised assessment is required because BLM and the US Fish and Wildlife Service determined that the number of tortoises impacted by the project would far exceed the 38 expected to be killed or displaced by construction and operation. The assessment provides detailed estimates of the number of tortoises that might be killed, harassed (marked, handled, etc), translocated (moved a distance away from where it was found), or held in quarantine.

Capture/Collect:

BLM now anticipates capturing and collecting about 162 adult tortoises (animals that are 160mm or larger).

At least 60, but as many as 90 non-adult tortoises (smaller than 160mm) will be captured, although this represents only a fraction of the expected non-adult population on the project site. The rest are likely to go unnoticed during surveys and end up crushed by construction activity.

Kills:

Up to 700 non-adult tortoises during the 3 year construction phase are expected to die. Non-adult tortoises are difficult to spot and remove from burrows, resulting in an estimated 90% mortality rate due to construction.

BLM estimates up to 9 adult tortoises (160mm or larger) will be killed during the 3 year construction phase.

Harassment:

BLM anticipates harassing 1,025 adult tortoises, and 2,349 non-adult tortoises, bringing the total number to over 3,000.

Defined as any sort of handling, marking or relocation, harassment is the broadest category assessed in the BLM report, and covers tortoises impacted over an area much larger than just the project site. The total area includes the project site, the locations that receive translocated tortoises, and identified control sites.

Why are there so many tortoises?

The previous tortoise surveys were conducted during drought years, which made it difficult for biologists to acquire accurate numbers. However, during the environmental review process for the project, desert experts highlighted the pristine and high quality nature of the habitat, arguing that another site should be found for the solar power project. The high number of tortoises is confirmation of this assessment.

Since most of the tortoises that will be impacted by the project are juveniles, this is also a testament to the health of the tortoise population in the Ivanpah Valley, showing that it is reproducing. Most hatchling tortoises do not survive to become adults due to predation and other natural causes, but the solar power project assures that an even higher number of juveniles will not reach adulthood.

Overall, the high tortoise density is a tribute to the Ivanpah Valley's ecological health. The BrightSource project should never have been approved for this location in the first place.

Where will they be moved?
The BLM will face increased difficulty finding places to move so many tortoises. Relocating tortoises to habitat nearby will only put stress on the tortoises already resident there, increasing competition for resources. Other experts are concerned that some areas identified to receive tortoises may not be of sufficient habitat quality or are too close to Interstate 15, which presents a hazard to tortoises and drivers. Furthermore, tortoises that are moved far from their home range are more likely to die with a couple years.

A separate document from the California Energy Commission (CEC) confirmed that two tortoises died as a result of construction activity over the past two months. One juvenile tortoise was found crushed in the middle of a road, and another died of heat stress, possibly as it tried to return to its home range which had already been bulldozed and cleared of shade-providing vegetation. Another tortoise was found with unnatural lacerations on one of its legs and bleeding profusely. That tortoise survived after receiving treatment, according to the CEC report. Certainly many more juvenile tortoises have already been killed, but their deaths have gone unnoticed because of their small size and small burrows.

What's next?

The US Fish and Wildlife Service is reviewing the revised biological assessment, and reserves the right to call "jeopardy," essentially halting further construction or limiting the project to just the initial phase. The Fish and Wildlife Service could also simply modify the incidental "take" permit--which says how many endangered species BrightSource Energy is allowed to displace or kill--and let the project proceed.

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